


Onyx's FUSW 2020

by OnyxSinz (OnyxianDrake)



Category: Undertale (Video Game)
Genre: Alternate Universe - Swapfell (Undertale), Alternate Universe - Underfell (Undertale), Alternate Universe - Underlust (Undertale), Alternate Universe - Underswap (Undertale), Break Up, Cold, Death Threats, Distance, FUSW 2020, Fucked Up Sansby Week 2020, Implied/Referenced Rape/Non-con, M/M, Post-it Notes, Sharp, Smut, Strangulation, Threats of Violence, Ungrateful, Unhealthy Coping Mechanisms, Unhealthy Relationships, needy, note, private
Language: English
Status: Completed
Published: 2020-10-03
Updated: 2020-10-07
Packaged: 2021-03-08 01:21:02
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 7
Words: 1,220
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26787349
Author URL: https://archiveofourown.org/users/OnyxianDrake/pseuds/OnyxSinz
Summary: Figured I might as well try my hand at some Sansby! Even if it is unhealthy~
Relationships: Grillby/Sans (Undertale), Sansby
Comments: 2
Kudos: 21





	1. Private - Undertale Sansby

**Author's Note:**

> I don't really write Sansby so these will probably all be short(100-300 words) but I wanted to write unhealthy stuff...
> 
> So uh, here it is? I'll specify each AU and prompt in the chapter titles!!
> 
> Also, I love all comments but replying terrifies me so just know I'm not ignoring anyone <3 I see you and I appreciate you!!!!

"I just... don't need Papyrus knowing."

Sans flinched faintly at the sharp crackle Grillby gave, forced to meet the intense stare the bartender was giving him.

"What does that have to do with the rest of Snowdin?"

"They talk, G!" Sans whined as he rubbed the back of his neck, eyelights avoidant now. "Please, can we just...keep it private?"

"You do that well enough, considering you leave the minute we're finished," Grillby snapped back. "You drink, you eat, we fuck, you leave. Is that what you're expecting? Free food because we're fucking."

Sans couldn't avoid the moment of hesitation, but it was enough to make the elemental's flames turn a dark red at the edges. The hostility made Sans curl into himself.

"I-It's not like that-"

"Get out."

Sans ducked his head as he took the warning and demand to heart, gone before Grillby could even blink at him.


	2. Needy - Underlust Sansby

“G, again, please~”

“ _ Really? _ ”

“W-what?”

Grillby huffed as he pulled back a fraction. Sans shuddered at the slightest movement of the elemental, his magic overly sensitive from the previous orgasms.

“We fucked two days ago and you’re already this needy. What the hell spiked your LT this bad?”

Sans didn’t have anything to say to that, his hips still tried to roll up against Grillby’s. He knew he’d be sore the next day, but it’d give him an excuse to sleep the day away. To avoid certain...thoughts that kept plaguing his skull.

“Sans?”

He jolted hearing his name, cheeks flushed from more than just arousal now. Sans avoided looking Grillby in the eyes, instead he simply pulled the elemental down into a kiss. The heat of his partner’s tongue was a good distraction, just as much as the sex usually was. He just needed it for a little longer.


	3. Ungrateful - Underfell Sansby

**Notes for the Chapter:**

> Some content warnings this chapter: referenced/inferred non-con, strangulation, threats

“What the hell do you mean  _ no? _ ”

Sans flinched at the tight grip Grillby had on his jaw. He matched the elemental’s glare with one of his own as he snarled in turn.

“Means I ain’t fuckin’ you to pay off my tab! An’ don’ fuckin’ touch me!”

His attempt to shove Grillby off only resulted in his hands pinned over his head. He had to freeze at the firm grip around his throat, his eyelights shrunk as his sockets widened. Sans shuddered when Grillby got close to his face, the purple flames dancing too close for comfort to his face.

“Ungrateful waste of space.”

Sans jolted when the hand squeezed around his throat. His sockets stung in warning, skull feeling stuffy and light at the lack of magic circulation. Finally, Grillby let go and left him to gasp for air more for comfort than need.

“Now,” Sans jumped when a hot hand pressed against his pubic arch through his shorts in warning, “we’re going to make a deal to pay off that tab, or you aren't going home tonight.”


	4. Cold - Undertale Sansby

“Hey, Grillbz.”

“...Papyrus told me you were sick.”

Sans shrugged weakly as he leaned on the bar. He knew well enough it wasn’t uncommon for him to fall ill with his HP, and that Grillby was well aware of the fact too.

“Nothin’ contagious, same cold I get every few weeks or so.”

“And you came in while sick because…?”

Sans blinked at the elemental owlishly, surprised at the question as he raised a brow in return.

“Because I wanted to stop in and say hi? Maybe eat some fries?”

“Don’t expect me to keep an eye on you.”

Sans’ grin faltered at that while his confusion only rose, “You seem to be acting awfully  _ cold _ yourself, G.”

“I’m working, I don’t have time to make sure you’re not about to puke or pass out on my bar.”

“I wouldn’t come here if I was throwing up,” Sans huffed. “Guess I’ll just leave if it bothers you that much.”

“Good.”


	5. Note - Underlust Sansby

**Notes for the Chapter:**

> This prompt piggybacks off of the original Underlust one on Day 2.

_ hey g, sorry i left before u could wake up. not feelin too hot today, probs gonna stay home so dont expect me tonight. maybe tomorrow if i feel up 2 dancin or a little hot under the collar ;) _

Grillby frowned at the nearly illegible scrawl of Sans’ handwriting. He crumpled up the note and burned it to ash, dumping the remains in the trash as he got ready. One too many times now, Sans had up and vanished before he could wake up to talk. He was tired of the avoidance, so in his opinion, it was about damn time to give Sans a taste of his own medicine.

-

“Sans! Grillby left a note on the door!”

Sans groaned, his bones ached and itched with unwashed crustiness as he sat up and hobbled downstairs. He plucked off the note Papyrus had left stuck to the inside of the door with a frown.

_ Don’t bother coming over unless you plan on talking instead of fucking. _

_ Hope you feel better, Grillby. _


	6. Sharp - Swapfell Sansby

**Notes for the Chapter:**

> Has anyone else done Swapfell Sansby before??? I don't think I've seen it :0

“ _Fuck_ , your claws are sharp.”

Sans huffed as he fastened the straps of his chest piece, glancing at Grillby in the mirror he was facing.

“You’re the one who decided I shouldn’t wear my gloves,” he retorted shortly as he pulled on his pants.

“I didn’t think you’d tear up my back!”

Sans slapped away the deep blue flames that tried to grab at his gloves before he could get them on. He poised them in warning like a taunt he would claw Grillby if he tried again, sockets squinted as he sneered towards the elemental.

“Touch my shit and I’ll tear something else of yours!”

He growled lowly as he pulled them on when Grillby chuckled and walked away to retrieve his own shirt. Sans couldn’t help but eye the brighter claw marks highlighting his back, smirking to himself as he slipped on the gloves.

Maybe he’d dare to bite next time, his teeth were just sharp as well~


	7. Distance - Underswap Sansby

**Notes for the Chapter:**

> Longest one at 250 words!!! I kept these all short on purpose, and I had fun doing them!!!

“You’re...moving?”

Sans wasn’t sure how to feel when Grillby nodded, the bright green elemental shyly shutting the door behind him. Sans still caught a glimpse of all the boxes in the house, telling of just how long he had been preparing for leaving.

“I didn’t want to stress you with your work at the embassy, so I didn’t see it important enough to tell you until now.”

“...Where are you moving to?”

Sans hated the waver in his voice, how his smile felt too painful and heavy to keep plastered on his face.

“Some northern state called Pennsylvania. They want me there to oversee the monster candy being made at a partner company’s factory.”

Sans nodded slowly, trying not to wince at just how far it was.

“That’s...a long distance you have to go. Maybe Papy and I can visit you sometime!”

Grillby looked away, not meeting Sans in the eye now as he adjusted his glasses, “...I’m not sure you should visit at all, Sans.”

“...What?”

“You have embassy work, I’ll be overseeing a factory and candy manufacturing, we’ll both have busy schedules. It doesn’t work out on the surface like it did Underground.”

“That doesn’t mean it couldn’t work!”

“Sans...it’s over, okay? It’s less stress to just...break up sooner rather than later. No hard feelings then, right?”

“I guess not…”

“...I need to finish up packing.”

“Right! S-Sorry...hope you have a good day, G.”

“You too, Sans. Bye.”

“Yeah...bye.”

The door closed.


End file.
